"A few years ago, we decided we wanted to travel the world, so we started living a simpler life to make up the savings," Ms Harvey said.
"We downsized our rental property, sold one of our cars, got rid of paid TV like Sky Sports and just watched our general lifestyle spending. Also, my husband worked away for long periods, which helped towards our savings goals."
The family left Australia 14 months ago and have visited more 20 countries since, including Borneo, China, Japan, the Maldives, New Zealand, Sri Lanka and the USA.
Be spontaneous to seize the best opportunities
They share their extraordinary journey on their Instagram account, @WhereAreWeGoingTomorrowTravel, which is a nod to their habit of travelling spontaneously and often not deciding on the next destination until the night before.
"We got our Instagram name from Sophie as she was always asking every night 'where are we going tomorrow?'," Ms Harvey said.
"Some of the highlights have been snorkelling the beautiful Great Barrier Reef in April 2018 and then we were skiing down a volcano in New Zealand in May 2018.
"In September 2018 we took a sea plane to the Maldives. In October 2018 we took the famous train Ella to Kandy in Sri Lanka and got to see wild elephants. We also saw pygmy elephants and orang-utans in Borneo.
"Highlights of 2019 so far have been camping in Yosemite National Park, USA in February, walking parts of the Great Wall of China and cycling around the lake of Mount Fuji in Japan in April. Then throughout May we have been island hopping around Asia.
"Finally, we absolutely love Disney and have been lucky to visit all five international Disney resorts including hopping aboard two Disney cruises."
Ms Harvey said she and her husband were spontaneous travellers who just "book flights and accommodation as we go".
Most of the time it's sorted the day before or day of because this way if we like a place and want to stay longer we can and if we don't we can just move on," she said.
The family typically spends about three weeks in one place, depending on what there is to do there.
Low points on a year of travel
The biggest hurdle they've faced was during the earthquakes in Indonesia on Gili Island in August 2018, when much of the area was devastated and the family's hotel roof collapsed.
The family had to run to higher ground on the island, which made them question their decision to travel.
"We were terrified during the Indonesian earthquake, we had two very young children to protect and there we were climbing up to the highest point of the island and sleeping under the starts with nothing more than the clothes on our backs," Ms Harvey said.
"We spoke about stopping travelling for a long time during and shortly after the event, but we had worked so hard for this and it was a chance of a lifetime opportunity and we are so glad we decided to keep going.
"Although we have settled on going back to Ireland to be with our family once our travel fund runs out, we still have a list of places we would like to see such as Vietnam, Cambodia and Laos to name a few."
Parting advice to other families
Ms Harvey said she had helped other people with advice and tips about travelling with their children.
"If you're thinking of doing this, just go for it. Even with young children it's totally possible to travel the world," she said.
"We have had no problems providing our children's needs. They have adapted so well to all these different environments. I'd just make sure you get good travel insurance and make sensible choices.
"We have never looked back or regretted taking the leap to travel full time. It has opened our eyes and made us better and stronger people for it.
"Some people think we were crazy for packing up our bags and quitting our jobs to take two small kids around the world, but at worst if it didn't work out we could simply just go home,and it will have just been like a big long holiday.
"Never put yourself in a position where in the future you'll look back and think 'we could have done that, but instead we did this'."
